Sheetsxsheet i



Dec. 30, 1952 A. A. HOLLAND DEHYDRATION 0F MINERAL sALTs AND THE LIKE 2SHEETS--SHEET 1 Original Filed Nov. 3, 1948 Dec. 30, 1952 A. A. HOLLANDRe 23,608

DEHYDRATION 0F MINERAL sALTs AND THE LIKE:-

original Filed Nov. s, 1948 2 SHEETS- SHEET 2 BMM #Horn ey,

Resaued Dec. 30, 1952 DEHYMDRA'I'IOIT` OF MINERAL SALTS AND THE LIKEArthur A. Holland, Pensacola, Fla.

Original No. 2,578,355, dated December 11, 1951,

Serial No. 58,097, November 3. 1948. Application for reissue June 19,1952, Serial No. 294,525. In Canadav October 8, 1948 s claims. (c1. 15s-2) Matter enclosed in heavy brackets appears in the original patent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

This invention relates to the dehydration of salts in aqueous solutionand is particularly directed to the treatment of salts, Alike sodiumsulphate, which melt in their own Water of crystallization.

Many methods have been proposed for the extraction of sodium sulphatefrom its naturally occurring aqueous solutions but-there aredifficulties in the economical extraction of the salt. Much heat isrequired and the caking of the salt on the walls and other parts of thedrier offers diiliculty and adds to the cost of the operation.

The object of the presentinvention is to providean improved method andapparatus for vdehydrating of such salts. While the invention isparticularly described with ,reference to the ex-v traction of sodiumsulphate it will be ajgnparent` that it is useful for dehydrating othermaterials and is to be so interpreted.

It has been found that the encrusting or caking of the salt on thedrying equipment as well as the evaporation, and thus the efficiency ofthe procedure, is largely determined by the particular manner in whichthe body of salt solution is handled and the particles thereof.projected into f the drying atmosphere.

The invention will be described with reference to the accompanyingdrawings in which Figurel is a side elevation in section of theapparatus,

Figure 2 is a plan view in section,

Figure 3 is an end elevationin section, and

Figure 4 is an end elevation offtlie spray de- In the drawing, Irepresents a drying chamber having the confined zone 2 and the largerzone 3 in communication through the opening 4. The brinefeed inlet is at5 and the hot gases inlet at 6. A spray device 'I is locatedlongitudinally of zone 2 and preferably at each side-thereof as bestshown in Figures 2 and 3. Located between and parallel with the spraydevices is a scraper conveyor 8 mounted on a sprocket 9 carried by ashaft I driven by the pulley I3 and ,a tail sprocket II on the shaft I2.Scrapers I4 are carried by the conveyor. The spray zone 2 is verticallyoonfined by the top wall I which is curved downwardly at its forward endto the outlet passage 4 leading to the larger expansion zoned in therear end of which is the drainage* battle I5. The

height of the expansion zone is preferably twice that of the spray zone.K

The spray device, two of which are used in the form shown in Figures l,2 and 3, comprises a drum IT mounted for rotation on a driven shaft I8.Circumferentially arranged on the drum are spiral blades I9 and betweenthe adjacent blades is formed a series of cup-like compartments 20 bymeans of the transverse walls 2|.

At the outlet end of the drier the conveyor 8 discharges over theupwardly inclined ramp 22 and lip 23 into a collecting chamber .24 inwhich is a discharging conveyor 25, 261s the outlet for theexpansionvchamber 3 through which. vapors are exhausted.

In operation the'material to be dried is fed into the drying .chamberthrough the inlet conveyor 5.. preferablyat a rate to'provide a liquidlevel below the surface of the drum 1 on which the spiral blades andcup-like compartments are arranged. The amount of liquid Apicked up` byeach cup-like .compartment in the spray device and the speed at whichthe spray device is rotated determines the size of the sprayed liquidparticles andthe extent to which caking or encrustation of the salt isprevented within the conned spray zone. 'I'his cup-like arrangement ofthe spray device provides a relatively coarse rain-like spray which ismuch more effective in preventing caking than a iine spray, such as thatdelivered by a drum revolving in contact with the solution. It has beenfound that when the linear velocity of solution leaving the cups is atleast 8,000 feet per minute encrustation is effectively` prevented byuse of this spraying device. The actual velocity varies with the size ofthe confined.` spray chamber as this affects the distance the, sprayedparticles have to travel to contact theA wallsqof the chamber. Hot gasespassedinto the spray chamberpick up the moisture from the sprayedparticles and carry it through the,v expansion zone 3 to the exhaustoutlet 2E. ,Because ofthe reduced rate of travel through.. the.expansion zone mechanically sus'- pended particles of solution aresegregated and rain back-into the mass under treatment.

As the solution is concentrated the salt crystallizes out and iscontinuously removed by the scraper conveyor and discharged from thedrier, thus avoiding the tendency for it to redissolve in the remainingmass. The drying gas used may be from direct fired burner or the exhaustgases from other source.

This manner of spraying the mass to be dried and of vcirculating thedrying gases is found efcientlyto utilize the heat energy in the dryinggaseous medium as indicated by the fact that the temperature of theexhaust gases is normally not more than 20 higher than that of thesolution being sprayed.

It will be apparent that the spray device may be used in other specificforms of the drying chamber.

What is claimed is:

1. Dehydrating apparatus comprising a-drying chamber, a spray devicemounted longitudinally of the chamber at each side adjacent the bottomthereof, said spray device comprising a rotatably mounted drum, a.spiral blade mounted longitudinally on the drum, and a plurality of thetransverse wallsI between adjacent flights of the blade each extending.from the .periphery thereof to the drum to form cup-like compartik mentscircumferentially disposed between adjacent flights of the blade, and aconveyor extending longitudinally of the chamber and located between thespray devices. c

2. Dehydrating apparatus comprising means for drying gases, meansfor'feeding material to be dried to the drying chamber, and a conveyorfor discharging dried material extending longitudinally of said .sprayzone and "below said spraying device.

3. Dehydrating apparatus comprising a'drying chamber, a spray.device'mounted longitudinally of the chamber adjacent the bottomthereof, said spray device comprising a .rotatably` mounted drum, aspiral blade mounted longitudinally on the drum, and a plurality oftransverse walls between adjacent nights of the blade each extendingfrom the periphery thereof to the drum to form cup-like compartmentscircumferentially disposed between adjacent ilights of the blade, and aconveyor extending longitudinally of the .chamber and located below thespray device.

e. Dehydrating apparatus comprising a drying chamber, aspray devicemounted longitudinally of the chamber adjacent the bottom thereof and inwidely spaced relation to the top thereof to provide a spraying' vzonein said chamber above said device, said spray device 'comprisingarotat-A ably mounted drum. extending from end to 'end of the chamber, aspiral blade mounted longitudinally on the drum andextending from end toend thereof, and a plurality of imperforate transverse walls betweeneac-h adjacent flight of the blade each extending from the 'peripherythereof to the drum to form cup-like compartments circumferentiallydisposed between. adjacent flights of the blade.

5. Apparatus for treating fluid materials comprising a chamber arrangedto receive a current of gases, a liquid spraying device mounted in thechamber `adjacent the bottom thereof and in widely spaced relation tothe top thereof to provide a spraying sone in said chamber above saiddevice, said spray device `comprising a rotatably mounted drum extendingfrom end to end of the chamber, a spiral blade mounted longitudinallyonl the drum and extending from end to end thereof, and a plurality ofimperforate transverse walls between each adjacent flight of the bladeleach extending from the periphery thereof to the. drum to form cup-likecompartments circumferentially disposed between adjacent flights of theblade.

6'. Apparatus-for. treating fluid materials -ernpris-ing a chamber-having an ,inletspaced from thev bottom thereof and arranged to delivera current of gases to said chamber, a liquid spraying device mounted inthe' chamber adjacent the bottom thereof, below said inlet, and linwidely spaced relation to the topY thereof to provide' a spraying zonein 'said' chamber above said device vfor traversal by said current 0fgases, said spray de vice comprising a 'rotatably' mounted drum`esctending from end to end of the chamber, and a spiral blade mountedlongitudinally on the drum and extending from endto end thereof, andaplurality of transverse walls between each ad# jacent flight of theblade forming cup-like compartments Acircamferentiallg/ disposed betweenadjacent flights of the vblactejsaid chamber havingan inlet for'supplying liquid to the bottom portionv of said chamber for entrainmentby said compartments, said compartments being in free. communicationwith said 'spraying eonefor def` livery thereto of rain-like particlesof said liquid.-v

l ARTHUR 1A, HOLLAND." "i

'REFERENCES onEn l UNITED STATES PATENTS Number Name Date 426,361Buttne'r et al. Apr. 22, 189D 501,048 Bassett July'll, 1893 1,091,464Wagner Mar. v24, .1914

. 1,190,127 Dsdier July 4, 1916' 1,720,786 1i'ast'ing V July 16, 1929 i1,730,902 Rugh Oct. 8, 1929 :1,992,520 Colton et al.-` Feb. '26, 1935Pranke June 2, 1936 VogelJorgensen Jan. 26, 1937 vfilari' et al. f'Ma11..10.,.111942 `:Eat'ockharn Apr. .7, ..1942 Davey Jan. 12, ..1943

Peebles` Mar. 2, 1943 l'2,384,998 lHal'igh' Sept; 18, 1945 2,397,818Tausch Apr. 2, 1946

